


The Little Lost Star

by grelleswife



Series: Dadbastian Week 2019 [8]
Category: Kuroshitsuji | Black Butler, とつくにの少女 | Totsukuni no Shoujo | The Girl from the Other Side (Manga)
Genre: Cosmic Forces, Crossover, Dadbastian Week, Eventual Happy Ending, Fluff and Angst, Found Family, Gen, Magic, O!Ciel is about 5 years old in this verse, O!Ciel's name is Astre in this AU, Parent-Child Relationship, Platonic Relationships, but i didn't include the ship in the tags because Agni died under tragic circumstances, i tweaked the lore a bit as needed, not sebaciel, there's also sort of Sebagni, you don't have to read The Girl from the Other Side to understand the plot but it's recommended
Language: English
Status: In-Progress
Published: 2019-11-27
Updated: 2019-11-27
Packaged: 2021-02-26 04:09:09
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,654
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21587374
Author URL: https://archiveofourown.org/users/grelleswife/pseuds/grelleswife
Summary: Ensconced in walled cities, humans cower in fear of the mysterious "cursed ones" who roam the land. In an abandoned village outside these walls, however, a cursed one named Sebastian and a young boy named Astre live in harmony. When their peaceful existence is disrupted by forces that wish for Astre's destruction, Sebastian must do everything in his power to protect his tiny charge. But who is this star-child, and can he and Sebastian escape the dread hand of fate?
Relationships: Sebastian Michaelis & Ciel Phantomhive
Series: Dadbastian Week 2019 [8]
Series URL: https://archiveofourown.org/series/1547587
Comments: 9
Kudos: 32





	The Little Lost Star

**Author's Note:**

> Written for the Dadbastian Week "stars" prompt, though the celestial connection isn't quite as obvious in the first few chapters.
> 
> This AU is heavily based on Nagabe's manga The Girl from the Other Side, although I have altered numerous elements of the lore and plot to fit the story. While a knowledge of Totsukuni no Shoujo is not required to understand The Little Lost Star, I highly recommend this beautiful and unusual manga if you enjoy "found family" stories involving human children and magical creatures!

Astre propped up his chin in his hands, watching the rain stream from the sky in silvery torrents. Rivulets of water trickled down the cottage windowpane and plashed onto the ground, forming puddles here and there like tiny lakes. _Shush_ , _shush_ , the rain whispered. He listened closely to see if it had other words to share, but the deluge repeated itself like a forgetful old woman. _Shush, shush_.

“You won’t be able to play outside today, I fear.”

Astre turned his head and saw that Sebastian had walked over to stand behind him.

“That’s okay! I stayed inside all the time back home b’cause I got sick so much. There’s lots of things we can play,” he reassured his guardian. Sebastian was the sort of grownup who worried about things he wouldn’t talk about—a little like Papa—so Astre tried not to do anything that might make him sad. He spun around and gave Sebastian a biiiig smile just to make sure the cursed one knew he really was okay. 

Cursed one. Until a few months ago, Astre thought that cursed ones were evil and scary, but Sebastian was nice, even if he looked a little strange. He was thin and taller than Papa. Black as coal _all_ over. His outline didn’t stay still; it was smoky and blurred, like the shifting air above a fire. Except for the color, Sebastian’s body was sort of like an insider’s, but he had glowing red eyes, pointy teeth (Sebastian called them “fangs”), sharp claws, and a skinny tail with a spike at the end. He also had long, twisty horns that reminded Astre of an animal he had seen in one of his picture books (an “antelope,” maybe?) and shiny black hair. Astre liked Sebastian’s wings best of all. He had _six_! They were H U G E, and covered in pretty feathers. Astre wished he could pet them, but you couldn’t touch cursed ones. The first time Astre had seen them, he’d told Sebastian that they were like angel wings. The cursed one had just laughed, though his eyes had gotten that lost look that made Astre’s heart hurt.

“Let’s play hide-and-seek!” Astre suggested, hopping down from the windowsill.

Sebastian smiled. “I’m the seeker, I assume?”

“Of _course_ , silly. You’re way too big to hide in the house,” Astre explained patiently. There weren’t many spots where someone Sebastian’s size could hide, and the game wouldn’t be fun if it was too easy.

“Ah, yes, you’re right. My apologies.”

The cursed one covered his eyes with his left hand, the one that had the weird purple marks on it. “I’ll give you til the count of ten.”

Astre scooted around him and skipped away, giggling with excitement. He had the perfect hiding place in mind. Even Sebastian would never find him there! In the house’s guest bedroom, there was a stately wooden wardrobe. One thing Astre had noticed about the door was that it opened to the inside. A grown-up couldn’t fit in the space between the door and the inner wardrobe wall…but a kid could! Astre scampered into the room and made a beeline for the wardrobe. Luckily for him, the door was already open a crack, so he wouldn’t have to stretch up to turn the knob.

“Seven…”

Astre _verrrrry_ carefully squeezed his way inside. If he made too much noise, Sebastian might hear him, and he didn’t want to lose because of something silly like that. There was enough light coming in for him to spot a fur coat that had fallen off its hanger.

“Nine…”

Astre snatched up the coat, scurried over to the corner by the door’s hinges, and threw the coat over himself. It smelled a little musty, but at least it was cozy and warm.

“Ten! Ready or not, here I come, young Astre!”

Astre didn’t move a muscle, listening as Sebastian’s footsteps approached the room. Closer…closer…

“Hmm, where could he be, I wonder?”

Then the _creak_ of the door slowly swinging open. The boy huddled under the coat with baited breath, clapping both hands over his mouth to stop himself from laughing. A very very _very_ long pause…

“This would make an excellent hiding place, but it looks like young Astre is elsewhere,” the cursed one finally declared, his voice tinged with disappointment.

Astre couldn’t take it any longer. He had to show his guardian what a great trick he’d played!

“Here I am!” Flinging aside the coat, he dashed out from behind the door, clasped his hands behind his back, and grinned up at Sebastian. The cursed one laughed, his pretty wings fanning outwards and his tail twitching the way it did when he was really happy.

“Goodness, there you are. It seems I’ve been outfoxed.”

“Out-foxed?”

“Tricked. You fooled me just now, young Astre. You’re a clever boy.”

Astre cheerfully bounced on the balls of his feet. Back home, Ciel usually got most of the praise and attention since he was the heir, the bold, strong twin everyone liked best. But Sebastian, one of the smartest grownups Astre knew besides Papa, thought that _he_ was clever? It was better than getting a slice of chocolate cake from Tanaka!

Following a few more rounds of hide and seek, they whiled away the rest of the afternoon with other pastimes. They played dress-up with the old clothes left behind by the people who’d lived in the house before. Sebastian had to fold up his wings super tight to get the clothes to fit (unlike his everyday clothes, he hadn’t ripped holes in the back of these for them to poke through), but he looked good, especially in the flowery dress he chose as his last outfit. Astre had fun trying on the bonnets and hats, though they were all too big and kept slipping off.

Next came drawing, one of Astre’s favorite things. Sebastian had found paper and pencils galore the last time he went “foraging” in another abandoned village, which meant that Astre could scribble down all the ideas he’d been keeping in his head. As soon as Sebastian gave him the supplies, Astre set to work, creating starry skies and wondrous monsters that never were. Astre went quiet, lost in the magical movement of pencil against paper, lines coming together to bring his dreams to life. The cursed one sat close by (though far enough away so they wouldn’t accidentally touch), watching him.

“I know I’ve said this before, but you truly have a gift, child,” Sebastian remarked as he examined Astre’s latest piece, which showed a boy in a long robe and crown sitting on a boat in the middle of a huge mountain lake, holding a star in his hands. Astre always included more fine detail than most children his age, which made his drawings look like they’d been made by someone years older (at least, that’s what Mama and Papa used to tell him, with proud smiles showing he’d done a _really_ good job).

Astre grinned, biting his lower lip bashfully. “They just kinda happen. I don’t know where the ideas come from. There are so many!” Ciel could do tons of things that Astre couldn’t—like run around outside without falling down and coughing—but, when it came to drawing, Astre was king.

His stomach growled.

“Sounds like it’s dinnertime, at least for you,” Sebastian chuckled. Like all cursed ones, Astre’s guardian didn’t need food or water, or even sleep (Astre wished he could stay up late like Sebastian!), but he did his best to make sure Astre had plenty to eat. He helped Astre gather his drawings and took them to Astre’s room, where they’d hang them up on the walls later. “You’re a growing boy, so it’s high time you had something to eat. Would you care for some stew?”

* * *

_We’ve come a long way_ , Sebastian reflected as Astre helped him lay out the ingredients for that evening’s dinner. Out of his usual caution, Sebastian kept his wings tucked away and accepted vegetables from the child’s proffered hand with infinite care so as not to brush against his skin. When he’d first brought Astre to this abandoned cottage about a month ago, Sebastian had only the haziest notion of how to cook. If it hadn’t been for a small stockpile of bread and the cups of milk with honey that the cursed one managed to prepare, the poor boy would have been hungry indeed. Thankfully, the previous inhabitants had left behind a large book of recipes, which Sebastian was slowly beginning to master. Of course, the process hadn’t been easy—his early attempts at baking pies had ended in charred and blackened failure. Those setbacks aside, the cursed one was finally feeling more at ease in the kitchen. Astre smiled and thanked him profusely when presented with Sebastian’s culinary efforts, so perhaps he was improving. The cursed one couldn’t say for certain whether Astre really enjoyed his cooking, though. With his kind, loving heart, the boy probably wanted to spare Sebastian’s feelings, and the cursed one lacked the sense of taste necessary to check the seasoning.

Had he been able to cook when he was human? He wasn’t quite sure. That was another affliction of the curse. In addition to warping Sebastian’s appearance beyond all recognition, it had also robbed him of his memories. They were as blurred and illegible as the pages of a book left out in the rain, the tale contained therein reduced to smears and swirls of ink. The cursed one retained his powers of speech and reason, as well as his ability to read and write, but the vital details of his life had been obliterated. Even his name was lost to the void. The cursed one wasn’t really “Sebastian”; that was just the appellation Astre had given him when he’d found the boy wandering alone in the forest, clutching a storybook to his chest. When the cursed one had informed Astre that he had no name, the child declared without missing a beat, ‘I’m gonna call you Sebastian, then! ‘Cause you’re black all over just like our guard dog at home.’

Now and then, though, a memory would briefly reemerge like a fish swimming up toward the surface of a pond only to flit down into darkness when Sebastian tried to catch it. One such recollection came to him as he stirred the stew. This was…familiar…

_He gripped a wooden spoon, lily-white fingers slender and elegant. He stirred the…not stew…curry! Yes, that’s what this fragrant dish was,_ curry _—slowly and methodically. A man stood behind him, his brown hand guiding and cradling Sebastian’s. The smaller man blushed when his companion bent down to kiss his cheek._

_‘See? Making curry isn’t that hard,’ the man laughed, his voice rich and deep. ‘Before you know it, you’ll be better at it than me.’_

_‘I doubt that, dear. We academics are more suited to books and blackboards than the kitchen! And I don’t think I could rival the “Right Hand of Kali.”’_

_‘Have more faith in yourself, moonlight. You’re brilliant. If you can understand Latin and mathematical theorems and all the other things you teach those Weston boys, learning this will be child’s play.’_

_The warm words of praise made Sebastian glow, and he leaned back into his partner’s embrace._

_‘Well, even if I can’t, I’ll always have you to make it for me.’_

_A laugh, a kiss planted at the base of his jaw. ‘Of course you will! I’m not going anywhere, my honey.’_

Sebastian’s chest was lanced by an intense feeling of…sorrow? Anguish? His free hand balled into a fist as he fought the impulse to fall to his knees and double over in pain.

“Sebastian? Are you okay?”

The cursed one turned from the pot of stew to see Astre staring at him with wide, anxious eyes.

“Nothing’s the matter, young Astre, not to worry,” he choked out, unable to meet the child’s worried gaze.

“But somethin’s wrong, Sebastian. You were staring off into space, and your wings got all droopy,” Astre insisted. “And your eyes look sad, like you’re hurt.”

An astute, sensitive child. By Sebastian’s reckoning, Astre couldn’t be older than five or six, but he was wise beyond his years. Very little escaped the notice of those bright blue eyes.

“I…merely forgot the last steps of the recipe for a moment, but I’m fine now. Truly,” Sebastian assured him with more vehemence than was strictly necessary.

Astre didn’t seem convinced, but he nodded and returned to doodling on a spare piece of paper he’d brought to the table, humming softly to himself.

_Who was that man?_ Sebastian wondered in frustration as he returned his attention to the bubbling stew. It was maddening how much the curse had stolen from him. The cursed one was sure of two things, however. First, that man had been dear to him, as dear as his own heart. Second, through some cruel twist of fate now unknown, Sebastian had lost him forever.

* * *

The mood lightened a bit during dinner. Astre proclaimed that the stew was “yummy!” and enthusiastically mopped up the leftovers with a hunk of bread. That radiant smile could banish the bleakest despair. Sebastian took a few minutes to clean the dishes and then lit a fire in the parlor’s fireplace, dragging two worn but comfortable red armchairs close to it for warmth—the rain had made the night air chillier than usual. He then moved a small table between the chairs, and Astre excitedly ran over with the chessboard clutched in his tiny hands. Astre plunked the board down on the table and used a stool Sebastian had procured for him to climb into the armchair. It was too high off the ground for a small boy to reach it with ease, and, when the cursed one was quite literally unable to lend him a helping hand, they had to improvise.

Sebastian had been surprised to learn that such a young child enjoyed playing chess, but, with his innate intelligence, he was no slouch. The cursed one apparently had an extensive knowledge of the game (what a bitter irony that the only things he remembered with clarity were trivial ones!), but he’d been trounced by little Astre on more than one occasion. Tonight, Sebastian maintained the upper hand, but his victories were hard-won. After each match, he carefully explained to Astre what strategic mistakes he’d made that had allowed Sebastian to prevail. Astre listened intently, eyes twinkling. “I’m gonna win tomorrow night for sure!”

“We shall see, young Astre, but it’s about time you went to bed,” Sebastian smiled, tugging at the chain around his neck and checking his silver pocket watch. It was the only possession besides the shirt and trousers he’d been wearing that had remained to him when he “awoke” as a cursed one. The watch was beautiful but sent a pang of nostalgia through him. Was it connected to that mysterious man who had tenderly guided his hand?

Astre groaned. “Do I _have_ to? I’m not sleepy.”

“If you’re good and go straight to bed, I’ll read you a story from your book.”

Instantly transformed into a dutiful cherub, Astre hopped off the armchair and practically ran to his bedroom. Sebastian fetched a lantern to place on the nightstand (Astre was afraid of the dark and unable to sleep without a light) and laid out the boy’s nightclothes. Luckily, the family who’d lived here before must have had children around Astre’s age, since there were several nightgowns and other outfits that fit him reasonably well.

As Aster cuddled beneath the blankets and blue quilt, Sebastian pulled up a small wooden chair, seating himself and picked up the boy’s treasured book from the nightstand. It was bound in azure-blue leather, with silver designs resembling constellations stamped on the front and gilt-edged pages.

"What story will we have tonight, young Astre?"

“Umm….the story ‘bout where the cursed ones came from,” Astre decided after a moment of reflection.

Sebastian gingerly turned the pages, using a light touch so as not to rip his ward’s beloved book with his talons.

“In the beginning, two gods ruled the world as equals. The white god governed the movement of the heavens and the symphony of the spheres, while her companion, the black god, oversaw the earth and all the creatures that lived and moved upon it. Over time, however, the black god grew mischievous and restless. He began playing tricks on the white god, disrupting the celestial choirs and stealing the divine instruments she used to maintain order in the sky. In a rage, the white god placed a curse on the black god, transforming him into a hideous monster and branding him with a seal so that all would know of his crimes. Embittered by his ugly appearance, the black god fled to the dark, wild forests where no humans dwelled, nursing his anger until it turned to madness. Seeing mortals devote their worship to the white god, he swore revenge, sending his curse forth into the ranks of men. Humans touched by the curse were marked with the violet brand on their left hand and were turned into horrible black beasts—the cursed ones. To save themselves from annihilation by the curse, those humans that remained built vast walls around their cities and drove out the cursed ones to live outside these fortresses, roaming the earth in desolation. That is how it came to pass that humans, the worshipers of the white god, became known as “insiders,” and the cursed brethren of the black god were soon called “outsiders,” the monsters with no place to rest their head.”

Sebastian glanced up and saw that Astre had dozed off, his breathing steady and even. So much for not being sleepy! Sebastian gently closed the book and put it back on the nightstand. What an adorable child Astre was. A frail creature, but with a sweet, gentle heart. Affectionately, Sebastian reached out to pet that slate-grey hair before coming to his senses. _Do you_ want _to blight him, you fool?!_

The cursed one gazed at his clawed, blackened hand, marred by the violet seal of the curse, and was overcome with a wave of melancholy. Less than a foot separated him from the little boy who slept contentedly beneath the faded quilt, but that distance might as well have been an infinite ocean.

_You’re cursed, Sebastian_ , he reminded himself, reinforcing a truth more bitter than rue and as immutable as the relentless passage of time itself. _No matter how much you may want to, you can never reach him._

He and Astre walked in parallel, always side by side, but forever unable to touch.

Sebastian slipped out of the room and walked quietly to his study. The room was filled with knickknacks—peculiar creatures preserved in jars, feathers and brightly-colored stones, and stacks and stacks of journals. The journals were of the greatest interest to Sebastian. Whoever had written in them seemed to have been attempting a complete history of the insiders and their conflicts with the outsiders, and the cursed one had found them to be highly insightful. Tonight, however, Sebastian ignored them in favor of the single handwritten letter that he kept on the desk. He’d found it in the pages of Astre’s book shortly after meeting his ward, though the boy himself had paid it little mind. The cursed one had read it dozens of times since then and pored through the journals in search of some clue as to its meaning, but all for naught. Nonetheless, he sat at his desk and perused its contents yet again.

_Kind stranger,_

_Not even the gods know for certain what will become of us. However, there are times when providence reveals fragments of the future to me, broken splinters from time’s mirror. I have an ominous premonition that, by the time you read this letter, my family and I will have met a violent end. This is why I have left my son Astre alone in the woods Outside. I do not expect you to excuse my actions, but this child must live. Please, kind stranger, protect him. My intuition tells me that he will need a sword and shield in the days to come. I dare not say too much, but he bears the power of the heavens. For that reason, there are those who wish my son dead._

_—Vincent Phantomhive, the Queen’s Watchdog_

Sebastian put his head in his hands. He didn’t have the courage to share these contents with Astre. As far as the boy knew, his Papa had taken him outside the walls late one night “for something important, but he wouldn’t tell me what it was.” Vincent had left Astre in a small clearing, promising to return soon and that someone would be taking care of him until Papa came back. Since Sebastian had inadvertently discovered Astre the next day while roaming the forest, the boy still believed his father’s words. After all, a “nice cursed one” had appeared to look after him, so of course Papa was telling the truth. Sebastian had a sinking feeling that Vincent’s prediction had been correct, but how the hell was he supposed to tell this tenderhearted child that his entire family had most likely perished? The mere thought of his devastated face…Sebastian couldn’t bear it. So he put off Astre’s inquiries with feeble excuses. Surely his papa would come next week. Or the week after that. Or the week after that. He couldn’t maintain the charade forever, though, especially not with an intelligent boy like Astre. And what exactly had Vincent meant when he said that Astre possessed “the power of the heavens?”

More troubling, what unknown enemy felt so threatened by this power that they were prepared to kill his boy?


End file.
